I'm using WL, and it seems as though you can use multiple widgets on your lock screen. The only limitation I can see is the available area to place widgets. (I guess the size of the widgets would also be a limitation.) Right now I have a date/clock widget (HD Widgets), a Power Toggles widget, and a WL (custom) slider. The slider is used to unlock the phone, and can have other options. The only buggy behavior I've noticed is, every once in a while, when I swipe the slider to unlock the phone, the default lock screen appears and I have to swipe a second time. It doesn't happen too often, so it's not a big deal to me.
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